Crushing plant

ABSTRACT

Input material comprised of stone, gravel or other material to be crushed is screened at a receiving station to separate the largest pieces of input material into two different sizes. The largest pieces are fed into an adjacent primary crusher at one of a plurality of zones at which crushing takes place. The second largest pieces are conducted past said first designated crushing zone, in overhead relation thereto, and delivered to crushing means at another zone. Screens located under the crushing means at each crushing zone vibrationally conduct carryover material thereon of larger than finish size to an elevator, from the discharge means of which crushed but still oversize material is fed to crushing means at one of said crushing zones other than said first designated crushing zone. The crushing plant has the customary primary and secondary crushers, and either or both of them can be comprised of first and second stage crushing devices.

limited States Patent 3,322,354 5/1967 Ostermann 241/81 3,409,23511/1968 Quinn 241/101 M Primary Examiner-Andrew R. J uhasz AssistantExaminer-Gary L. Smith Attorney-Ira Milton Jones ABSTRACT: inputmaterial comprised of stone, gravel or other material to be crushed isscreened at a receiving station to separate the largest pieces of inputmaterial into two different sizes. The largest pieces are fed into anadjacent primary crusher at one of a plurality of zones at whichcrushing takes place. The second largest pieces are conducted past saidfirst designated crushing zone, in overhead relation thereto, anddelivered to crushing means at another zone. Screens located under thecrushing means at each crushing zone vibrationaily conduct carryovermaterial thereon of larger than finish size to an elevator, from thedischarge means of which crushed but still oversize material is fed tocrushing means at one of said crushing zones other than said firstdesignated crushing zone. The crushing plant has the customary primaryand secondary crushers, and either or both of them can be comprised offirst and second stage crushing devices.

Jill Q PATENTEDunv 23 l97| F: 6 22.0 8 9 sum 1 [IF 5 CRUSHING PLANT Thisinvention relates to crushing plants of the type disclosed in my US.Pat. Nos. 3,073,536 of Jan. 15, 1963, and US. Pat. No. 3,409,235 Nov. 5,l968, and its object is to effect improvements in plants for crushingstone, gravel or other crushable materials, for the purpose of achievingspeedier processing of input materials and substantially increasedoutput.

in general, it is an objective of this invention to provide a stone orgravel crushing plant of the type referred to in my aforesaid patents,but which features an improved receiving unit for input material, alongwith associated structure by which any desired percentage of the finesthat comprise a substantial part of the input material can be separatedfrom the remainder thereof and either discarded or conducted to adelivery zone along with other finish material processed by the plant.

Another object of the invention is to provide a crushing plant of thetype referred to, wherein materials can be crushed at a plurality ofzones either forwardly or rearwardly of a rotary lift, or at both sidesof the lift if desired, to greatly increase the output of the crushingplant.

With these observations and objectives in mind, the manner in which theinvention achieves its purpose will be appreciated from the followingdescription and the accompanying drawings which exemplify the invention.

The accompanying drawings illustrate several complete examples ofembodiments of the invention constructed according to the best modes sofar devised for the practical application of the principles thereof, andin which:

F 10. 1 is a side elevational view of a crushing plant embodying thisinvention;

FlGS. 2a and 2b are enlarged side views of the rear and front portions,respectively, of the plant seen in FIG. 1, and partly in section;

FlG. 3 is a more or less diagrammatic rear end view of the lam; p FIG. 4is a side view of a crushing plant of modified construction, but havingits receiving end portion removed to avoid duplication; and

FIG. 5 is a view similar to FIG. 4 of a further modified embodiment ofthe invention.

Referring now to the accompanying drawings, the numeral generallydesignates the elongated horizontal frame upon which all of thecomponents of a crushing plant of this invention are mounted. In aportable plant such as shown, the frame consists of front and rear framesections 11 and 12, respectively, each provided with pairs of wheels 13so as to be capable of support independently of the other. The adjacentend portions of the frame sections are pinned together, as at 14, toenable them to be easily disconnected and transported separately fromone location to another.

Input material to be processed is loaded into a receiving unit 16mounted on the frame section 12 at its extreme rear end portion. Alsomounted on the rear frame section but at a location forwardly of thereceiving unit, is a primary crusher 17. The primary crusher is locatedjust behind the prime mover 18 from which it is driven. The prime mover18 is here shown as an internal combustion engine mounted on the frontof the rear frame section 12.

Mounted on the front frame section 11, reading from rear to frontthereof, is a rotary elevator or lift 19, a secondary crusher 20, andanother prime mover 21, again shown as an internal combustion engine.

It is to be understood, however, that the prime movers referred to abovecould be provided by electric motors receiving power from an off-plantdiesel electric unit, if desired.

The receiving unit 16 is comprised of superimposed upper and lowerhoppers 22 and 23, respectively, each open at its bottom. A grizzly 24extends forwardly and upwardly out of the top of the upper hopper 22,and it is positioned so that all input material loaded into thereceiving unit will fall onto the bars of the grizzly. The upper hopper22 comprises part of a vibratory screen device having an eccentricmechanism driven by a cross-shaft 25 which in turn is driven from theprime mover 18 in a conventional way. The vibratory screen device hasthree superimposed screens 26, 27 and 28 that are vibrated in the foreand aft direction by the eccentric mechanism to cause carryover materialof greater than finish size which fails to pass through the screens, tobe vibrationally advanced in the forward direction toward the primarycrusher l7.

The uppermost screen 26 is positioned horizontally beneath the grizzly24 to receive material that passes down between its bars. All but thelargest pieces of input material dumped onto the grizzly pass through itto fall onto the vibratory screen 26 there beneath. The largest piecesof input material are directed downwardly and rearwardly by the inclinedbars of the grizzly to fall onto a portion of the intermediate vibratoryscreen 27 that extends rearwardly beyond the upper screen 26. All thefines, such as sand and the like small particle size material, plusmaterials of so-called finish size, pass through the mesh of the upperand intermediate vibratory screens 26 and 27 and drop onto the lowervibratory screen 28. The lower screen 28 can have the smallest mesh ifthe fines are to be rejected, but it is otherwise sized to allow all thefines and finish size pieces of input material to pass downwardlytherethrough while preventing passage of larger than finish sizematerial.

The material passing through the lower screen 28 drops into the bottomhopper 23, which has a pair of side-by-side downwardly and outwardlyinclined discharge compartments with mouths 29 and 30 to separatelydirect the material onto the upper stretches of laterally adjacentendless conveyor belts 31 and 32 therebeneath. The conveyor belts extendlengthwise of the frame, under the receiving unit 16, and each istrained over a pair of rollers 34, one of which can be driven in eitherdirection by means of a reversible electric motor. Hence, the topstretch of either belt cab travel either forwardly or rearwardly of theframe, depending upon the direction in which its motor is operated.

ln this way, either conveyor belt 31 or 32 can be run in a direction toreject materials thereon by dumping-them over the rear end of the plant,when such materials are to be discarded; or when such materials are tobe saved and used, said conveyor can be run in the opposite direction todischarge the material thereon onto the rear section 35 of a deliveryconveyor 36, which carries the materials forwardly along the frame fordischarge at a delivery zone 37 at the front end of the plant.

All of the screens 26, 27 and 28 can be of /ta-inch or l-inch mesh whenthe fines are to be retained. However, if the fines are to be rejected,the bottom screen 28 is replaced by a screen of either V4-inch oris-inch mesh, and the finish size material is advanced forwardly thereonas carryover material to be discharged onto the rear portion of a screendeck 46. The fines that pass through the screen 28 are deposited ontothe conveyors 31-32 which are then run in the direction to discard thefines over the rear end of the frame.

It will be appreciated that it is possible, with the aforementionedarrangement of the conveyor belts 31 and 32, to have one belt givenforwardly while the other is simultaneously driven rearwardly. Moreover,by the adjustment of a flap valve 38 mounted in the lower hopper 23 on apivot bar 39 having a handle 40 on its rear end, different amounts ofthe fines can be directed onto either conveyor for keeping or fordiscard at the rear of the plant. This gives a wide range of choice inthe retention and/or rejection of fines; all can be retained or anydesired percentage thereof can be rejected, depending upon the directionthe conveyor belts 31 and 32 are driven and upon the adjustment of theflap valve 38.

The rear section 35 of the delivery conveyor 36 is mounted on the rearframe section beneath the primary crusher l7, and it dumps materials onthe upper stretch of its belt onto the rear end portion of the forwardsection 42 of the delivery conveyor. The forward section 42 is mountedon the front frame section 11, and it extends at an upward and forwardinclination, under the secondary crusher 20, from a level well beneaththe frame to a level a substantial distance above the frame and beyondthe front thereof. This assures the discharge of finish materials at arelatively high delivery zone and facilitates loading of such finishmaterial into trucks or other transit vehicles.

Also mounted on the frame under the primary crusher is a vibratoryscreen unit 44 having an upper screen deck 45, and the lower screen deck46 mentioned hereinbefore, both located over the rear section 35 of thedelivery or finish conveyor. The forward ends of both decks 45, 46extend into the open rear end of the rotary lift 19.

The rotary lift or elevator comprises a drum open at both ends, andmounted on pairs of rollers 47 at each side of the frame. The rollers atone side can be suitably driven by the forward prime mover, as from theinput shaft of the secondary crusher 20. The rotary lift is of thetwin-chambered type, having axially separated but adjacent rear andfront compartments 191 and 192, respectively.

The bottom deck 46 of the vibratory unit 44 extends rearwardly beyondthe rear of the upper deck 45 and under the bottom of an upright chute48 having its open upper end in position to receive carryover materialsfrom the forward end of the bottom screen 28 of the receiving unit 16.Hence, all carryover materials from the screen 28 are deposited on thebottom deck 46 of the vibratory unit 44, for passage of any finish sizematerial therethrough and deposit of the same on the rear section of thedelivery conveyor.

The forward end of the deck 46 on unit 44 projects into the rearcompartment 191 of the rotary lift 19, while the upper deck 45 extendsforwardly into the front compartment 192 of the rotary lift 19, from theopen rear thereof.

lt will also be noted that the primary crusher 17 is comprised of firstand second stage crushing devices 171 and 172, respectively. The firststage of the primary crusher is located rearwardly of the second stage,with its inlet in position to receive the largest pieces of inputmaterial vibrationally advance toward and 011' of the forward end of themiddle screen 27 of the receiving unit 16.

Crushed material discharges from the first stage of the primary crusheronto the rearwardly extending portion of the lower deck screen 46 of thevibratory unit 44, which functions to vibrationally advance all of thepieces of material that are larger than finish size forwardly into therear compartment 191 in the rotary lift 19.

The second stage 172 of the primary crusher is fed from the top screendeck 26 of the vibratory receiving unit 16. Carryover material on thetop deck 26, as stated, is of somewhat smaller size than the largestsize pieces of input material on the center deck 27. Carryover materialon the top deck 26 is vibrationally advanced forwardly to a short chute50, which is in the nature of an extension of the deck 26. Thiscarryover material is advanced along the chute and over the top of thefirst stage crushing device, in bypass relation thereto, and it isdirected by the chute into the upwardly opening inlet of the secondstage crushing device 172. Crushed material issuing from second stagecrushing device 172 discharges from the bottom thereof onto the rearportion of the upper deck 45 on the vibratory screen unit 44.

In this way, the largest pieces of input material are crushed in thefirst stage 171 of the primary crusher, while the second largest piecesof input material bypass the first crushing stage and flow directly intothe second stage 172 of the primary crusher. Material of finish size andsmaller passes downwardly through decks 45 and 46 of the vibratoryscreen unit 44 to drop onto the rear section 35 of the finish conveyor.

Carryover material on the top deck 45 of the vibratory unit 44 isusually comprised of pieces that are smaller than those that remain onthe lower deck 46 of said unit. The larger pieces are discharged intothe rear compartment 191 of the rotary elevator 19, while the smallercarryover pieces are vibrationally carried forwardly by the top screen45, through the rear compartment 191 of the rotary lift, and dischargedinto the forward compartment 192 of the lift.

The materials thus received in the elevator wheel 19 are lifted upwardlythereby to discharge zones at its top. There, the material from thefront compartment drops down onto the rear of the upper one 51 of a pairof endless conveyors, and the material from the rear compartment dropsdown onto the rear of the lower one 52 of said conveyors. The conveyors51 and 52 are of the endless belt type, and they extend upwardly andforwardly out of the open front of the rotary lift 19 to zones above thesecondary crusher 20.

The secondary crusher 20 also has two crushing stages. While the primarycrusher has been shown merely by wary of example as comprising atwin-chambered jaw crusher that provides first and second stage crushingdevices, the secondary crusher can, for example, comprise a triple rollcrusher having coarse first and fine second stage crushing rolls 53 and54, respectively, cooperating with a common crushing roll 55.

The inlet of the first stage of the secondary crusher opens upwardly tothe left of the roll 53; and the inlet of the second stage of thesecondary crusher likewise opens upwardly, but to the right of the roll53. A chute 56 can be located at each inlet, to direct materialthereinto.

The upper conveyor 51 carries material forwardly over and past the topcrushing roll 53 for discharge into the inlet of the second stage of thesecondary crusher; while the lower conveyor 52 discharges into the inletof the first stage of the secondary crusher, behind the roll 53.

Materials issuing from both stages of the secondary crusher dischargefrom its bottom onto a screen 58 beneath the secondary crusher but abovethe forward section 42 of the delivery conveyor.

Materials of finish size pass through the screen 58 and drop onto theforward section 42 of the delivery conveyor therebeneath.

The screen 58 extends rearwardly into the open front of the rotary lift19, to discharge oversize carryover material thereon into the frontcompartment 192 of the lift. Such flow of carryover materials into therotary lift is facilitated by mounting the screen in a downwardly andrearwardly inclined attitude on the frame. However, the screen maycomprise part of another vibratory unit, generally designated 60, whichcan be driven from the prime mover 21 via input shaft of the secondarycrusher.

lt will thus be appreciated that the forward compartment 192 of therotary lift 19 receives oversize material from both the secondarycrusher and from the second stage 172 of the primary crusher; while therear compartment 191 of the rotary lift receives oversize material fromonly the first stage 171 of the primary crusher 17.

The crushing plant illustrated in FIG. 4 differs from that previouslydescribed only in the arrangement and type of crushing units employedtherein. However, crushing is also effected at several zones spacedapart lengthwise of the plant. For this purpose, primary crushing isagain accomplished in two stages, by means of a first stage crusher 271,and a separate second stage crusher 272 spaced forwardly of the firststage crusher and substantially close to the rear of the rotary lift 19.These crushers can be individually driven by electric motors, not shown,powered from an off-plant diesel electric generator.

The secondary crusher has only one stage, and it is mounted on the framea distance forwardly of the elevator 19 but behind the prime mover 21 atthe extreme front of the plant.

As before, the largest pieces of input material are sorted out by thegrizzly 24 and are carried forwardly on the vibratory center screen deck27 of the receiving unit directly into the inlet of the first primarycrushing stage 271. The next largest pieces of input material are, asbefore, vibrationally advanced forwardly along the top screen deck 26 ofthe receiving unit and onto a vibrating chute which in effect provides asubstantial forward extension of the top screen deck. The chute 150extends forwardly over the top of the first primary crushing stage 271,and it bridges the space between the latter and the second primarycrushing stage 272. The forward end portion of the chute 150 is angleddownwardly somewhat, and it directs materials thereon into the upwardlyopening inlet of the second primary crushing stage 272.

Again in this embodiment of the invention oversize pieces of crushedmaterial issuing from the first primary crushing stage, along withfinish size pieces of material from the lower screen deck 28 of thereceiving unit, drop onto the screen deck 46 of the vibratory unit 44.All larger than finish size material remains on the screen 46 to bevibrationally advanced thereby forwardly into the rear compartment 191of the twin-chambered rotary lift 19. Such material is dischargedadjacent to the top of the rotary lift and falls onto a chute 70supported on the plant in a position of downward and rearwardinclination, so as to direct material out of the upper portion of therear compartment in the lift to the inlet of the second primary crushingstage 272. Consequently, such oversize material is fed into the secondprimary crushing stage to be reduced in size by its passagetherethrough.

The crushed material issuing from the bottom of the second primary stagecrusher 272 drops onto the vibratory screen 45, which as before, extendsinto the open rear of the rotary lift, near its bottom, and through therear compartment 191 to the front compartment 1192. Consequently,materials of finish size pass downwardly through the screen 45, whileoversize materials thereon are vibrationally conducted forwardly therebyand discharged into the forward compartment 192 of the rotary lift 19along with oversize material deposited on the screen 58 from the bottomdischarge of the secondary crusher 120. Such oversize material chargedinto the forward compartment of the rotary lift 19 is dischargedadjacent to the top of the lift, onto a belt conveyor 151 similar to theconveyor 51 described previously. The conveyor 151, of course, ismounted on the plant in an upwardly and forwardly inclined attitude,with its rear end inside the upper portion of the forward liftcompartment 192 and its forward end in position to discharge materialsinto the inlet of the secondary crusher 120.

The triple vibratory screen deck receiving unit 16, with its grizzly 24,is also an important feature of the plant illustrated in FIG. 4, and isalso used to advantage in the crushing plant illustrated in FIG. 5. Thelatter differs from those described earlier primarily in that it isprovided with single stage primary and secondary crushers 270 and 220,respectively, and a single compartment rotary lift 190. In the absenceof a second primary crusher stage, the upper screen deck 45 on thevibratory unit 144 can be eliminated, as only one screen deck 46 beneaththe single stage primary crusher 270 is needed. in this case too, animperforate vibratory deck beneath the screen deck 46 takes the place ofthe rear section of the delivery conve or.

Also in the FIG. 5 embodiment of the invention, the second largestpieces of input material that are vibrationally conducted forwardly onthe top screen deck 26 of the receiving unit, are caused to be deliveredto crushing means at a crush ing zone located forwardly of the crushingdevice closest to the receiving unit, in bypass relation to said closestcrushing device and over the top thereof.

In this case, however, the single stage primary crusher provides thecrushing means which is closest to the receiving unit 16, while thesingle stage secondary crusher 220 provides the crushing means which islocated at a crushing zone spaced forwardly of the primary crusher.

To achieve the above-described flow of material, the belt conveyor 251by which materials are conducted from the rotary lift 190 to the inletof the secondary crusher 220 extends rearwardly through the rotary lift190 far enough to receive all the materials elevated by the lift, and toalso receive materials directed thereonto from a small hopper 75. A beltconveyor 76 which extends over the top of the prime mover is is mountedon the plant in an upwardly and forwardly inclined attitude, in positionto dump into the hopper 75 and to receive the second largest pieces ofinput material from a short chute 250, like that seen in the FIG. 1embodiment. The chute 250 bridges the space between the top screen deck26 of the receiving unit 16 and the rear of the conveyor 76, and it canalso be formed as an extension of the deck 26 to vibrate fore and afttherewith.

From the foregoing description, together with the accompanying drawings,it will be readily appreciated by those skilled in the art that thisinvention provides a material-receiving unit which sorts input materialinto a number of difierent sizes, and further provides means by whichsuch material is conducted forwardly through the plant along a pluralityof paths that lead to crushing devices at zones spaced lengthwise of theplant, so as to achieve faster processing of the material and greateroutput than was possible with crushing plants heretofore available.

Those skilled in the art will appreciate that the invention can beembodied in forms other than as herein disclosed for purposes ofillustration.

The invention is defined by the following claims:

1. A crushing plant of the type having an elongated frame withlengthwise spaced first and second crushing means thereon, and havingconveyor means beneath said crushing means for receiving and conductingmaterials of finish size to a delivery zone, characterized by:

A. material receiving and classifying means mounted on the frameadjacent to said first crushing means and comprising superimposedmaterial screening members disposed at three different levels,

1. the topmost screening member being the coarsest and being adapted todischarge carryover materials that fail to pass therethrough onto thelower level one of the remaining screening members, in bypass relationto the upper level one of said remaining screening members,

2. said upper level screening member being positioned to receivematerials which pass through the topmost screening member and havingmesh no smaller than that of said lower level screening member,

3. and said upper and lower level screening members comprising decks ofa vibratory unit which effects vibrational advance of carryovermaterials on said upper and lower level decks in a direction toward saidfirst crushing means;

B. means for effecting discharge of carryover material vibrationallyadvanced along said lower level deck into said first crushing means;

C. and means extending over said first crushing means for effectingdelivery of carryover material vibrationally advanced along said upperlevel deck into said second crushing means.

2. A crushing plant of the type having an elongated frame with crushingmeans thereon at a plurality of stations spaced from one anotherlengthwise of the frame, and having conveyor means beneath said crushingmeans for receiving and conducting materials of finish size to adelivery zone, characterized by:

A. material receiving and classifying means mounted on the rear endportion of the frame, behind but adjacent to a first one of saidstations, comprising superimposed material screening members at threedifferent levels,

I. the topmost screening member being the coarsest and being adapted fordischarge of materials that pass therethrough onto the upper level oneof the remaining screening members, and for discharge of carryovermaterials that fail to pass through it onto the lower level one of saidremaining screening members, in bypass relation to said upper levelscreening member,

2. said upper level screening member having mesh no smaller than that ofsaid lower level screening member,

3. and said upper and lower level screening members comprising decks ofa vibratory unit that vibrationally effects advance of carryovermaterials on each of said decks in a direction forwardly of the frame,toward said first station;

B. means for effecting discharge of carryover material vibrationallyadvanced by said lower level deck into the crushing means at said firststation;

C. and means extending forwardly over said first station for effectingdelivery of carryover material vibrationally advanced by said upperlevel deck into the crushing means at a second one of said stations.

3. The crushing plant of claim 2, further characterized by:

A. said lower level deck extending rearwardly beyond the upper leveldeck and said topmost member;

B. and said topmost member having a discharge end which extendsrearwardly beyond said upper level deck and over the rearward extensionof said lower level deck so that carryover materials on the topmostmember will discharge onto the lower level deck in bypass relation tosaid upper level deck.

4. The crushing plant of claim 3, wherein said topmost screening membercomprises a grizzly which is tilted downwardly and rearwardly towardsaid rearward extension of the lower level deck so as to direct theretocarryover material that fails to pass through the grizzly.

5. The crushing plant of claim 2, further characterized by:

A. said vibratory unit having a third screen deck of fine mesh undersaid lower level deck to receive materials passing through the latter,said third deck being adapted to pass and thus separate fines from thematerial being processed;

B. a pair of side-by-side belt conveyors beneath said third deck, eachextending lengthwise of the frame and adapted to either conduct finesdropping thereonto from said third deck forwardly onto said conveyormeans or rearwardly ofi of the plant as reject material, depending uponthe direction in which the conveyor is run;

C. and means providing for selectively directing the bulk of the finespassing through said third deck onto one or the other of said conveyors.

1. THE TOPMOST SCREENING MEMBER BEING THE COARSEST AND BEING ADAPTED TODISCHARGE CARRYOVER MATERIALS THAT FAIL TO PASS THERETHROUGH ONTO THELOWER LEVEL ONE OF THE REMAINING SCREENING MEMBERS, IN BYPASS RELATIONTO THE UPPER LEVEL ONE OF SAID REMAINING SCREENING MEMBERS,
 1. Acrushing plant of the type having an elongated frame with lengthwisespaced first and second crushing means thereon, and having conveyormeans beneath said crushing means for receiving and conducting materialsof finish size to a delivery zone, characterized by: A. materialreceiving and classifying means mounted on the frame adjacent to saidfirst crushing means and comprising superimposed material screeningmembers disposed at three different levels,
 2. said upper levelscreening member being positioned to receive materials which passthrough the topmost screening member and having mesh no smaller thanthat of said lower level screening member,
 2. SAID UPPER LEVEL SCREENINGMEMBER BEING POSITIONED TO RECEIVE MATERIALS WHICH PASS THROUGH THETOPMOST SCREENING MEMBER AND HAVING MESH NO SMALLER THAN THAT OF SAIDLOWER LEVEL SCREENING MEMBER,
 2. A crushing plant of the type having anelongated frame with crushing means thereon at a plurality of stationsspaced from one another lengthwise of the frame, and having conveyormeans beneath said crushing means for receiving and conducting materialsof finish size to a delivery zone, characterized by: A. materialreceiving and classifying means mounted on the rear end portion of theframe, behind but adjacent to a first one of said stations, comprisingsuperimposed material screening members at three different levels, 2.said upper level screening member having mesh no smaller than that ofsaid lower level screening member,
 3. and said upper and lower levelscreening members comprising decks of a vibratory unit thatvibrationally effects advance of carryover materials on each of saiddecks in a direction forwardly of the frame, toward said first station;B. means for effecting discharge of carryover material vibrationallyadvanced by said lower level deck into the crushing means at said firststation; C. and means extending forwardly over said first station foreffecting delivery of carryover material vibrationally advanced by saidupper level deck into the crushing means at a second one of saidstations.
 3. The crushing plant of claim 2, further characterized by: A.said lower level deck extending rearwardly beyond the upper level deckand said topmost member; B. and said topmost member having a dischargeend which extends rearwardly beyond said upper level deck and over therearward extension of said lower level deck so that carryover materialson the topmost member will discharge onto the lower level deck in bypassrelation to said upper level deck.
 3. AND SAID UPPER AND LOWER LEVELSCREENING MEMBERS COMPRISING DECKS OF A VIBRATORY UNIT WHICH EFFECTSVIBRATIONAL ADVANCE OF CARRYOVER MATERIALS ON SAID UPPER AND LOWER LEVELDECKS IN A DIRECTION TOWARD SAID FIRST CRUSHING MEANS; B. means foreffecting discharge of carryover material vibrationally advanced alongsaid lower level deck into said first crushing means; C. and meansextending over said first crushing means for effecting delivery ofcarryover material vibrationally advanced along said upper level deckinto said second crushing means.
 3. and said upper and lower levelscreening members comprising decks of a vibratory unit which effectsvibrational advance of carryover materials on said upper and lower leveldecks in a direction toward said first crushing means; B. means foreffecting discharge of carryover material vibrationally advanced alongsaid lower level deck into said first crushing means; C. and meansextending over said first crushing means for effecting delivery ofcarryover material vibrationally advanced along said upper level deckinto said second crushing means.
 4. The crushing plant of claim 3,wherein said topmost screening member comprises a grizzly which istilted downwardly and rearwardly toward said rearward extension of thelower level deck so as to direct thereto carryover material that failsto pass through the grizzly.
 5. The crushing plant of claim 2, furthercharacterized by: A. said vibratory unit having a third screen deck offine mesh under said lower level deck to receive materials passingthrough the latter, said third deck being adapted to pass and thusseparate fines from the material being processed; B. a pair ofside-by-side belt conveyors beneath said third deck, each extendinglengthwise of the frame and adapted to either conduct fines droppingthereonto from said third deck forwardly onto said conveyor means orrearwardly off of the plant as reject material, depending upon thedirection in which the conveyor is run; C. and means providing forselectively directing the bulk of the fines passing through said thirddeck onto one or the other of said conveyors.